The present invention relates to a device for adapting a formwork element constituted by a formwork lining and at least two formwork beams to a given curvature of a circular formwork, the device comprising a web engaging the space between two formwork beams and a cross-piece fixed to the web and equipped with two parallel, spaced plates which project laterally beyond the web and overlap the formwork beams in the installed position, and whose projecting portions are provided with mounting lugs.
A device of this type has been known, for example in the form of the double-beam yoke marketed by the PERI company. These devices are used in connection with formwork elements for circular formwork which is to be adjusted to a given curvature radius of a concrete wall to be poured. In order to effect such adjustment, the devices are fixed to two formwork beams of the formwork element and interconnected by means of adjusting spindles. Then, the outer ends of the adjacent formwork beams are either moved towards or away from each other by corresponding actuation of the adjusting spindles, whereas the spacing between the lateral faces of the formwork beams, which are fixed to the formwork lining, remain constant at all times so that any operation of the adjusting spindle will cause the formwork element to bend and, consequently, cause the formwork lining to assume a curved surface. Given the fact that the formwork lining consists of a plane plate, the cantilevered ends of the formwork lining show the tendency to maintain their straightness, with the circular formwork element in this bent position, so that they will project tangentially from the outermost formwork beams. If, in the event of a circular formwork, these tangentially projecting contilevered ends were not corrected, the finished concrete wall would exhibit deviations from the desired curvature in the form of edged recesses or edged bulges.
One has, therefore, tried to force the cantilevered ends into the desired position, either by arranging formwork beams at the edge of the cantilevered ends or by providing pressure pieces on the formwork or by using junction ferrules with marginal-beam adjusting means. These correction elements are also fixed on the before-mentioned device and adjusted to the correct position, for example with the aid of adjusting spindles.
It is regarded as a drawback of these arrangements that considerable input of material and time is required for correcting the cantilevered ends of the formwork lining. In addition, the device described at the outset is connected with the disadvantage that a limited number only of adjusting spindles can be fixed on the device.